Environmental sustainability and economic benefits motivate increased use of recycled asphalt materials, including reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS), in asphalt pavements. However, adequate cracking performance initially and with time when these stiff, brittle, aged materials are added to virgin asphalt-aggregate mixtures must be maintained by engineering each unique materials combination of virgin and recycled materials. Recycling agents can be added to partially restore rheology and improve cracking performance of mixtures with high recycled materials contents, but performance must be balanced between rutting and cracking.
This webinar will summarize a forthcoming draft AASHTO Standard Practice for the use of recycling agents in asphalt mixtures with high recycled materials contents and provide: (1) component materials selection guidelines for virgin binders, recycling agents, and recycled materials (RAP and RAS) and their proportions; (2) a recycling agent dose selection method; (3) a binder availability factor for recycled materials for use in mix design; and (4) binder blend and mixture evaluation tools that include aging protocols, recycling agent incorporation methods, and laboratory tests and corresponding thresholds for balanced rutting and cracking performance.